Melanoplus spretusRocky Mountain Locust

Geographic Range

This species is now extinct. Its former range included the high, dry lands on the eastern slope of the Rocky Mountains. It extends from the southern tip of the true forests in British Columbia through Montana, Wyoming, Idaho, and the western parts of the Dakotas. There was also a sub-permanent region that the species invaded where it was only able to survive in for several years. This sub-permanent region extended east in British Colombia to include one-third of Manitoba, the Dakotas, the western half of Nebraska, and the northeast part of Colorado (Comstock, 1940)

Habitat

The habitat of the species was the high, drylands on the eastern slope of the Rocky Mountains. The species occured at elevations of 2,000 to 10,000 ft. It was unable to survive in low, moist areas for more than one generation. It was once found in greatest abundance in prairie lands with annual rainfall of less than 25 inches.

Physical Description

This species resembled the common grasshopper but was called a locust because of its migratory status. In general the Acridiinae (to which this species belonged) are recognizable by the presence of a distinct spine on the prosternum between their anterior legs. The family includes most of the larger short-horned grasshoppers. The Rocky Mountain locust averaged a length of 20-35 mm. It resembled the red-legged locust. It possessed a longer wing length that extended one-third beyond the tip of the abdomen. It also can be distinguised from the red-legged locust in that the apex of the last abdominal segment in males is notched. For comparision the red-legged locust is approximatly one inch long with a brownish body. The red-legged locust has clear hind wings and brownish fore wings. (Imms, 1948; Comstock, 1940)

Reproduction

The Rocky Mountain Locust female deposited eggs just below the surface of the soil using her strong oviposter. The eggs were enclosed in an oval or bean-shaped packet and enclosed with a glutinous substance. (Kellogg, 1905). The eggs were laid in the late summer and early fall and did not hatch until the following spring. The female laid 100 eggs or more at a time. When hatched the fledgling locusts were wingless for six to eight weeks and crawled around to find vegetation to devour. (Comstock, 1940; Meier, 1995)

Behavior

Though sometimes called a grasshopper, Melanoplus spretus was a locust because of its characteristic destructive migratory behavior. This species had rapid population increases and migrated en masse. (Little, 1957; Bland and Jacques, 1978; Kellogg, 1905)

Once the wild vegetation of their breeding ground was extinguished, and there was sufficient overcrowding, the locusts used their huge wings to migrate to lower and more fertile regions where it could find a better more abundant supply of food. This species was most noted for its huge swarms that played economic havoc on farmers' crops in the late 1800's (Comstock, 1940)

The species mades sounds by rubbing their hind legs together at rest. These calls were used for intraspecific communication (Kellogg, 1905)

Food Habits

The species was a migratory insect and with its many invasions of North America it had been seen eating almost all kinds of vegetation. The species had a particular taste for grains, and cereals. The wheat crop suffered from its huge swarms the most.(Meier, 1995) The only green plants that seemed to be spared from the specie's mandibles were tomatoes, castor beans, and raspberries. The species even consumed bark. (Kellogg, 1905)

Economic Importance for Humans: Negative

The species, as noted before, is the best known destructive migratory insect in the United States. Between 1873 and 1877 it caused more than $200 million in crop damages in Colorado, Nebraska, and other states. (Ryckman, 1999)

Conservation Status

This species disappeared in the space of 20 years. Starting with a massive swarm on July 20-30, 1874 and the last living specimen of the species was found in 1902. The end of the species can be traced back to its massive swarming periods and then its retreat to sandy river beds to breed. When the species went back to its habitat, farmers began to dig up the same ground to plant crops. When they did this they dug up thousands of their eggs and destroyed their breeding habitat. Other factors that are theorized to have caused the extinction of the locust are the decimation of bison and beaver populations. (Ryckman, 1999)

Other Comments

The Rocky Mountain Locust was once dreaded by farmers who had unluckily planted their crops in the path of these plant-eating beasts. They hold a place in The Guiness Book of World Records as "the greatest concentration of animals." An example of the size of one swarm was the swarm that swept through Nebraska in 1874. This swarm covered an approximate 198,000 square miles. This is twice the size of the state of Colorado. There were at least 12.5 trillion insects with a total weight of 27.5 million tons. Despite the great number or insects there are less than 300 specimens that were caught for inspection. Entomologists know where to find more: they look in frozen glaciers in the west. Many of these glaciers are called grasshopper glaciers because of the great number of insect bodies preserved in them.

(Ryckman 1999)

Contributors

Matthew Garcia (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Bland, R., H. Jacques. 1978. How to Know the Insects. New York, New York: Wm. C. Brown Company Publishers.

Comstock, H. 1940. An Introduction to Entomology. New York, New York: Comstock Publishing Company, Inc.

Imms, A. 1948. A General Textbook of Entomology. New York, New York: E.D. Dutton & Company, Inc..

Kellogg, V. 1905. American Insects. New York, New York: Henry Holt and Company.

Little, V. 1957. General and Applied Entomology. New York, New York: Harper & Brothers Publishing.

Meier, P. 04-17-95. Ate Everything but the Mortage - Grasshoppers wiped out four harvests, then vanished. Minneapolis Star Tribune.

Ryckman, L. 06-22-99. The Great Locust Mystery Grasshoppers That Ate The West Became Extinct. Denver Rocky Mountain News.